1. Field of the Invention
The invention relates to electromagnetic pulse distance measurement by the pulse transit time method wherein short electromagnetic transmission pulses are emitted at periodic transmission instants, the wanted echo pulse reflected by the object is established from the signals received in each transmission cycle after the transmission instant, and the transit time of the wanted echo pulse is determined as a measure of the distance to be measured.
2. Description of the Prior Art
From PCT publications WO 96/07928 and WO 96/19737 it is known particularly for measuring very short distances to strobe sample the signals received after the transmission instants in a sequence of transmission cycles whereby a sample is obtained in each transmission cycle at a sampling instant determined by a ramp function, the sampling instants exhibiting relative to the transmission instants in consecutive transmission cycles an increasing delay dictated by the linear increase of the ramp function. The samples obtained in sequence result in an image of the sampled received signal extended in time. In these known methods the ramp function is defined by a sawtooth signal generated by a ramp generator so that it is determined by the configuration of the ramp generator. There is thus no possibility of changing it as a function of the measurement result for adapting to differing conditions of application or for correcting deviations. It is likewise not possible to make use of some other sampling function instead of a ramp function.